Sulfonic esters of metal oxides and methods of their use

ABSTRACT

The present invention is directed to sulfonic esters of metal oxides including those of formulas I and II:

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 61/764,127, filed Feb. 13, 2013, the entirety of which is incorporated by reference herein.

TECHNICAL FIELD

The present invention is directed to sulfonic esters of metal oxides and their uses.

BACKGROUND

Corroles are tetrapyrrolic macrocycles:

Corroles are becoming increasing useful in the field of chemical synthesis as catalysts in, for example, oxidation, hydroxylation, hydroperoxidation, epoxidation, sulfoxidation, reduction, and group transfer reactions. See, e.g., Aviv, I., Gross, Z., Chem. Commun., 2007, 1987-1999. Based on their physico-chemical properties, it is envisioned that corroles could be useful in the sensors field and biomedical field. Id. Corrole-based materials useful in the chemical synthesis, sensor, biomedical, and other fields are needed.

SUMMARY

The present invention is directed to materials of formula I:

wherein A is a corrolyl or metallated corrolyl; M is a surface comprising TiO₂, BaTiO₃, SnO₂, Al₂O₃, Fe₂O₃, Fe₃O₄, ZrO₂, CeO₂, CdO, Cr₂O₃, CuO, MnO, Mn₂O₃, MnO₂, NiO, SnO, SnO₂, SiO₂, or ZnO; and n is 0 or 1.

The invention is also directed to materials according to formula II:

wherein B is —NCO, C₁₋₁₀alkyl, or

wherein R¹ is —COOH, —COOC₁₋₆alkyl, C₁₋₆alkyl, or aryl optionally substituted with halogen or C₁₋₆alkyl; M is a surface comprising TiO₂, BaTiO₃, SnO₂, Al₂O₃, Fe₂O₃, Fe₃O₄, ZrO₂, CeO₂, CdO, Cr₂O₃, CuO, MnO, Mn₂O₃, MnO₂, NiO, SnO, SnO₂, SiO₂, or ZnO; and n is 0 or 1.

Methods of making materials of formulas I and II are described herein. Also described are methods of using the materials of the invention in applications such as optical imaging.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts confocal fluorescence microscopy images of 1-TiO₂ [(a), (b), (c)], 1-Al—TiO₂ [(d), (e), (f)], and 1-Ga—TiO₂ [(d), (e), (f)].

FIG. 2 depicts transmission electron microscopic (TEM) images of TiO₂ nanoparticles of the invention before and after dye-functionalization. (a and d) Images of the initial TiO₂ nanoparticles. (b and e) Images of the nanoparticles after peroxide-etching. (c and f) Images of the nanoparticles after dye functionalization. The scale bar is 25 nm for the top row and 100 nm for the bottom row of images.

FIG. 3 depicts electronic absorption spectra for an amphiphilic corrole (H₃tpfc(SO₂OH)₂) and corrole-TiO₂ nanoconjates of the invention in phosphate buffer saline pH 7.4.

FIG. 4 depicts confocal fluorescence microscopic images of U87-Luc cells treated with 0.2 μg/mL of a preferred embodiment of the invention (1-Al—TiO₂) after 24 h (a), 48 h (b), and 72 h (c).

FIG. 5 depicts Z-stacked confocal fluorescence micrographic images of individual U87-Luc cells taken at 0.5-μm slice intervals after (a) 48 h and (b) 72 h of treatment with 0.2 μg/mL of a preferred embodiment of the invention (1-A—TiO₂).

FIG. 6 depicts a cell viability plot of U87-Luc cells treated by of a preferred embodiment of the invention (1-Al—TiO₂) at various concentrations (2 ng/mL to 2 mg/mL) using a bioluminescence assay.

FIG. 7 depicts the results of mouse primary hepatocytes (MPH) treated with a preferred embodiment of the invention (1-Al—TiO₂) in various concentrations (0.3 ng/mL to 0.3 mg/mL) for 24 and 48 h.

FIG. 8 depicts ATR-IR spectra for TiO₂ nanoparticles and preferred materials of the invention.

FIG. 9 depicts normalized ATR-IR spectra for TiO₂ nanoparticles and preferred materials of the invention.

FIG. 10 depicts X-ray photoelectron spectra for nanoconjugates 1-TiO₂, 1-Al—TiO₂, and 1-Ga—TiO₂ exhibiting the F(1s) band.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The present invention is directed to materials, preferably nanoparticulate materials, comprising a metal oxide covalently bonded to a corrole or metallated-corrole through an —SO₂α linkage. The metal oxides for use in making the materials of the invention include those having at least one —OH group. Such metal oxides are known in the art and are described in further detail below.

One embodiment of the invention is directed to materials according to formula I:

wherein A is a corrolyl or metallated corrolyl; M is a surface comprising TiO₂, BaTiO₃, SnO₂, Al₂O₃, Fe₂O₃, Fe₃O₄, ZrO₂, CeO₂, CdO, Cr₂O₃, CuO, MnO, Mn₂O₃, MnO₂, NiO, SnO, SnO₂, SiO₂, or ZnO; and n is 0 or 1.

Within the scope of the invention, M is a surface that comprises a metal oxide, for example, a metal oxide that comprises at least one —OH group. The —OH group can be inherently present on the surface. Alternatively, the at least one —OH group can be incorporated by oxidizing the surface with a reagent such as hydrogen peroxide. Preferred surfaces for use in the invention include metal oxides such as TiO₂, BaTiO₃, SnO₂, Al₂O₃, Fe₂O₃, Fe₃O₄, ZrO₂, CeO₂, CdO, Cr₂O₃, CuO, MnO, Mn₂O₃, MnO₂, NiO, SnO, SnO₂, SiO₂, and ZnO. In some embodiments, the surface comprises TiO₂. In some embodiments, the surface comprises BaTiO₃. In some embodiments, the surface comprises SnO₂. In some embodiments, the surface comprises Al₂O₃. In some embodiments, the surface comprises Fe₂O₃. In some embodiments, the surface comprises Fe₃O₄. In some embodiments, the surface comprises ZrO₂. In some embodiments, the surface comprises CeO₂. In some embodiments, the surface comprises CdO. In some embodiments, the surface comprises Cr₂O₃. In some embodiments, the surface comprises CuO. In some embodiments, the surface comprises MnO. In some embodiments, the surface comprises Mn₂O₃. In some embodiments, the surface comprises MnO₂. In some embodiments, the surface comprises NiO. In some embodiments, the surface comprises SnO. In some embodiments, the surface comprises SnO₂. In some embodiments, the surface comprises SiO₂. In some embodiments, the surface comprises ZnO.

In preferred embodiments, the surface is a nanoparticle surface.

In some embodiments, n is 0. In other embodiments, n is 1.

Corroles for use in the invention are known in the art and are of the general formula:

The corroles of the invention described herein can be attached to the M-OSO₂-moiety(ies) of the invention through any available carbon.

Particularly preferred corroles for use in the invention include those of the following general formula:

wherein Ar is an aryl group, for example, a phenyl or naphthyl group. In some embodiments of the invention, the aryl group is unsubstituted. In other embodiments, the aryl group is substituted. For example, when the aryl group is phenyl, the phenyl can be optionally substituted with halogen, for example, 1 to 5 halogen, that is, one or more of F, Cl, Br, or I, with F being a particularly preferred halogen. In exemplary embodiments, the aryl group is pentafluorophenyl. In other embodiments, when the aryl group is naphthyl, the naphthyl can be optionally substituted with 1 to 7 halogen, with F being a particularly preferred halogen.

Preferred corrolyls for use in the invention are those wherein Ar is pentafluorophenyl and include

In addition to being substituted with one or more halogens, the aryl group can be further substituted with —NR³R⁴, wherein R³ and R⁴ are each independently H, C₁₋₁₀alkyl, C₁₋₁₀alkenyl, or -alkaryl; or R³ and R⁴, together with the nitrogen atom to which they are attached, form a heterocycloalkyl ring, which may be optionally substituted with C₁₋₆alkyl, for example, methyl or ethyl. Examples of —NR³R⁴ moieties include:

Corroles incorporating an —NR³R⁴ substituted aryl group can be accessed using methods known in the art, for example, using nucleophic substitution reactions. See, e.g., Hori, T., Osuka, A. Eur. J. Org. Chem. 2010, 2379-2386. For example, corroles incorporating an —NR³R⁴ substituted aryl group can be accessed using the following synthetic scheme:

Amines that can be used in nucleophilic substitution reactions include, for example, benzylamine, octylamine, sec-butylamine, allylamine, dimethylamine, morphiline, piperidine, and N-methylpiperazine.

Another preferred corrole for use in the invention is of the general formula

wherein each R² is independently H, C₁₋₆alkyl, halogen, or M-O—SO₂—, wherein M is as described above.

Yet another preferred corrole for use in the invention is of the general formula

wherein Ar and R² are as previously described.

Corroles for use in the invention can also be metallated. In metallating a corrole, the nitrogens of the corrole are coordinated to a metal. Metals for use in the metallated corroles of the invention include any metal known in the art to be useful for coordinating to a corrole. Those of skill in the art understand that the function and use of the corrole can be modified by changing the coordinated metal.

For example, metals for use in metallating the corroles of the invention include Al, Ga, Fe, Mn, Sb, Co, Cr, Rh, Ru, Ro, Ir, V, Re, Cu, Sn, Ge, Ti, and Mo. Particularly preferred metals include Al and Ga. Another preferred metal is Fe. Yet another preferred metal is Mn. Another metal for use in the invention is Sb. Another metal for use in the invention is Co. Another metal for use in the invention is Cr. Another metal for use in the invention is Rh. Another metal for use in the invention is Ru. Another metal for use in the invention is Ro. Another metal for use in the invention is Ir. Another metal for use in the invention is V. Another metal for use in the invention is Re. Another metal for use in the invention is Cu. Another metal for use in the invention is Sn. Another metal for use in the invention is Ge. Another metal for use in the invention is Ti. Another metal for use in the invention is Mo.

The metals for use in metallating the corroles of the invention can be optionally coordinated to one or more ligands. Such ligands are known in the art and include, for example, pyridine, nitrosyl, imido, nitrido, oxo, ether, hydroxyl, chloride, carbonyl, fluoro, bromo, phenyl, iodo, phosphine, arsine, and the like. Those skilled in the art would readily be able to determine a suitable ligand for any particular metal. A particularly preferred ligand for use in the invention is pyridine. Preferred metal-ligand moieties include Al(ligand)₂ and Ga(ligand), with Al(pyridine)₂ and Ga(pyridine) being particularly preferred.

Exemplary materials of formula I according to the invention include:

wherein Ar is pentafluorophenyl. In particularly preferred embodiments, Ar is pentafluorophenyl and M is TiO₂.

While 2, 17 substituted corroles have been set forth herein, these examples are exemplary only and are not meant to limit the invention. It is envisioned that substitution at any position of the corrolyl or metallated corrolyl is within the scope of the invention.

Materials of formula I can be made according to the following method: contacting a surface comprising TiO₂, BaTiO₃, SnO₂, Al₂O₃, Fe₂O₃, Fe₃O₄, ZrO₂, CeO₂, CdO, Cr₂O₃, CuO, MnO, Mn₂O₃, MnO₂, NiO, SnO, SnO₂, SiO₂, or ZnO, the surface having at least one —OH group, with a compound of formula III: (Cl—SO₂)_(m)-A  (III)

wherein A is corrolyl or metallated corrolyl; and

wherein m is 1 or 2.

Preferably, the synthetic methods of the invention are conducted in an organic solvent such as pyridine, with heat.

Compounds of formula III can be prepared according to methods known in the art. See, e.g., (a) Mahammed, A.; Goldberg, I.; Gross, Z. Org. Lett. 2001, 3, 3443. (b) Saltsman, I.; Mahammed, A.; Goldberg, I.; Tkachecko, E.; Botoshansky, M.; Gross, Z. J. Am. Chem. Soc. 2002, 124, 7411. See also, Blumenfeld, C. M.; Grubbs, R. H.; Moats, R. A.; Gray, H. B.; Sorasaenee, K. Inorg. Chem. 2013, 52, 4774. One exemplary method of preparing compounds of formula III is shown in Scheme 1.

The corrole or metallated corrole used in any of the methods of preparing materials of formula I can be any of the corroles or metallated corroles described herein.

In preferred methods of the invention, the surface is a nanoparticle surface. In other preferred methods of the invention, the surface comprises TiO₂.

Corrole coupling to the metal oxide surfaces of the invention can be performed by mixing metals of the invention bearing hydroxylated surfaces, preferably in nanocrystal form, with solutions of corrole and heating, preferably to reflux. After repeated washing with copious amounts of solvent such as, for example, CH₂Cl₂, acetone, and water, and drying under vacuum, powders are obtained.

Preferred corroles for use in the methods of making materials of formula I include:

wherein Ar and R² are as set forth above.

Preferred metallated corroles for use in the methods of the invention include:

wherein Ar and R² are as set forth herein above and wherein D is Al, Ga, Fe, Mn, Sb, Co, Cr, Rh, Ru, Ro, Ir, V, Re, Cu, Sn, Ge, Ti, or Mo, each of which is optionally coordinated to one or more ligands. In preferred embodiments, D is Al(pyridine)₂ or Ga(pyridine).

The materials of the invention can be use in synthetic, biomedical, and optical imaging applications. In a preferred embodiment of the invention, the materials of formula I are used in imaging cancer in a patient. For example, a material according to formula I, wherein A is a metallated corrolyl, is administered to a patient. After a period of time sufficient for the material to be taken up by any cancer cells, the cancer cells within the patient are imaged using optical imaging, preferably using fluorescence imaging. Cancers that can be imaged using the methods of the invention will include glioblastoma, melanoma, breast cancer, liver cancer, and colon cancer.

Preferably, the materials used in the imaging methods of the invention include

wherein Ar is pentafluorophenyl and M is preferably TiO₂.

The materials of formula I of the invention can also be useful in other fields of endeavor by changing the coordinating metal in the metallated corrole. For example, materials of the invention can be useful in the hydroxylation and hydroperoxidation of alkanes. The materials of the invention are also useful in epoxidation and sulfoxidation reactions. The materials of the invention are also useful in catalysis, for example, reduction and group transfer catalysis.

In other embodiments, the materials of formula I of the invention are useful in corrole-based sensing applications and dye-sensitized solar cells. In other embodiments, the materials of formula I of the invention will have anticancer activity or will prevent cell death. In other embodiments, the materials of the invention are useful in singlet oxygen sensitization. In other embodiments, the materials of the invention are useful in lipo-protein protection and neuroprotection.

The invention is also directed to materials according to formula II:

wherein B is —NCO, C₁₋₁₀alkyl, or

wherein R¹ is —COOH, —COOC₁₋₆alkyl, C₁₋₆ alkyl, or aryl optionally substituted with halogen or C₁₋₆alkyl;

M is a surface comprising TiO₂, BaTiO₃, SnO₂, Al₂O₃, Fe₂O₃, Fe₃O₄, ZrO₂, CeO₂, CdO, Cr₂O₃, CuO, MnO, Mn₂O₃, MnO₂, NiO, SnO, SnO₂, SiO₂, or ZnO; and

n is 0 or 1.

Within the scope of the invention, M is a surface that comprises a metal oxide, for example, a metal oxide that comprises at least one —OH group. The —OH group can be inherently present on the surface. Alternatively, the at least one —OH group can be incorporated by oxidizing the surface with a reagent such as hydrogen peroxide. Preferred surfaces for use in the invention include TiO₂, BaTiO₃, SnO₂, Al₂O₃, Fe₂O₃, Fe₃O₄, ZrO₂, CeO₂, CdO, Cr₂O₃, CuO, MnO, Mn₂O₃, MnO₂, NiO, SnO, SnO₂, SiO₂, and ZnO. In some embodiments, the surface comprises TiO₂. In some embodiments, the surface comprises BaTiO₃. In some embodiments, the surface comprises SnO₂. In some embodiments, the surface comprises Al₂O₃. In some embodiments, the surface comprises Fe₂O₃. In some embodiments, the surface comprises Fe₃O₄. In some embodiments, the surface comprises ZrO₂. In some embodiments, the surface comprises CeO₂. In some embodiments, the surface comprises CdO. In some embodiments, the surface comprises Cr₂O₃. In some embodiments, the surface comprises CuO. In some embodiments, the surface comprises MnO. In some embodiments, the surface comprises Mn₂O₃. In some embodiments, the surface comprises MnO₂. In some embodiments, the surface comprises NiO. In some embodiments, the surface comprises SnO. In some embodiments, the surface comprises SnO₂. In some embodiments, the surface comprises SiO₂. In some embodiments, the surface comprises ZnO.

In preferred embodiments, the surface is a nanoparticle surface.

In some embodiments, n is 0. In other embodiments, n is 1.

In certain embodiments, B is —NCO.

In other embodiments, B is C₁₋₁₀alkyl, for example methyl, ethyl, propyl, butyl, sec-butyl, tert-butyl, pentyl, and the like.

In yet other embodiments, B is

wherein R¹ is —COOH, —COOC₁₋₆alkyl; C₁₋₆alkyl; or aryl optionally substituted with halogen or C₁₋₆alkyl.

In some embodiments, B is

wherein R¹ is —COOH.

In other embodiments, B is

wherein R¹ is —COOC₁₋₆alkyl, for example, —COOMe, —COOEt, —COOPr, —COOBu, and the like.

In other embodiments, B is

wherein R¹ is C₁₋₆alkyl, for example, methyl, ethyl, propyl, butyl, sec-butyl, tert-butyl, pentyl, and the like.

In yet other embodiments, B is

wherein R¹ is aryl, for example, phenyl or naphthyl. In these embodiments, the aryl can be optionally substituted with one or more substitutents selected from the group consisting of halogen and C₁₋₆alkyl.

In those embodiments wherein B is

B is preferably

Methods of making materials of formula II are also within the scope of the invention. According to the invention, materials of formula II can be prepared by contacting a surface comprising TiO₂, BaTiO₃, SnO₂, Al₂O₃, Fe₂O₃, Fe₃O₄, ZrO₂, CeO₂, CdO, Cr₂O₃, CuO, MnO, Mn₂O₃, MnO₂, NiO, SnO, SnO₂, SiO₂, or ZnO, the surface having at least one —OH group, with a compound of formula IV: Cl—SO₂—R  (IV) wherein R is —NCO or

wherein R¹ is —C(O)OH, —C(O)OC₁₋₆alkyl; C₁₋₆alkyl; or aryl optionally substituted with halogen or C₁₋₆alkyl.

Compounds of formula IV can be prepared using methods known in the art.

Materials of formula II are useful in the field of chemical synthesis, for example, as catalysts. Materials of formula II are also useful in the field of material science.

As used herein, the term “halogen” refers to F, Cl, Br, or I.

As used herein, “alkyl” refers to branched or straight-chain saturated aliphatic hydrocarbon groups having the specified number of carbon atoms. For example, C₁₋₁₀alkyl denotes an alkyl group having 1 to 10 carbon atoms. Preferred alkyl groups include methyl, ethyl, propyl, butyl, sec-butyl, tert-butyl, pentyl, hexyl, and the like.

As used herein “alkenyl” refers to hydrocarbon chains that include one or more double bonds.

As used herein, “aryl” refers to phenyl or naphthyl.

As used herein, “alkaryl” refers to an aryl moiety attached through an alkylene group, for example, benzyl (—CH₂-phenyl).

As used herein, “heterocycloalkyl” refers to a 5 to 7-membered monocyclic or bicyclic saturated ring that includes at least one heteroatom that is N, O, or S. Examples include piperidinyl, piperazinyl, morpholinyl, and pyrrolidinyl.

As used herein, “corrolyl” refers to a corrole moiety.

The following examples are presented in order to more fully illustrate the preferred embodiments of the invention. They should in no way be construed, however, as limiting the broad scope of the invention.

EXPERIMENTAL SECTION

Materials.

2 M AlMe₃ in toluene (Aldrich), GaCl₃ (Aldrich), HSO₃Cl (Aldrich), 21 nm nanopowder TiO₂ (Aldrich), 30% H₂O₂ (EMD) were obtained commercially and used as received. The starting material 5,10,15-tris(pentafluorophenyl) corrole (H₃tpfc) was prepared based on the literature method. The solvents pyridine and toluene were dried over a column. Acetone and dichloromethane used were both of reagent and spectroscopic grades depending on the applications. D-Luciferin potassium salt (Promega), Hoechst 34580 (Invitrogen™), Hoechst 33258 (Invitrogen™), Sytox Green (Invitrogen™), and FM® 1-43FX (Invitrogen™) were used as received according to the provider's instruction.

Chemical Preparation.

All preparations were carried out under Ar(g) atmosphere unless otherwise noted.

1. Corrole Preparation.

Preparation of 2,17-bischlorosulfonato-5,10,15-tris(pentafluorophenyl) corrole (H₃tpfc(SO₂Cl)₂; 1) was performed according to the literature procedure. The metallocorroles described in this study were prepared in the following manner.

1.1. Preparation of 1-Al.

To the 20-mL toluene solution of 0.32 g of 1 (0.32 mmol) in a round bottom flask was added 0.8 mL of 2 M AlMe3 (1.6 mmol) in toluene solution at an icebath temperature. The solution was stirred for 10 min followed by the addition of 1 mL anhydrous pyridine. The solution was allowed to stir for another 10 min over ice. The reaction was quenched by an addition of ice chips. The dark green solution was then extracted with CH₂Cl₂ and washed with water. The solvent was removed in vacuo and the dry deep green solid was redissolved in CH2Cl2 followed by filtration. The filtrate was brought to dryness to afford the dark green solid (0.098 g, 26% yield). ESI-MS (CH₂Cl₂): m/z: 1014.87 [M-H]⁻ (Calculated for C₃₇H₆N₄F₁₅Cl₂S₂O₄Al: 1015.88); ¹H-NMR (400 MHz, acetone-d₆, ppm): δ=9.76 (s, 1H), 9.25 (s, 1H), 8.97 (d, 1H), 8.85 (d, 1H), 8.70 (d, 1H), 8.58 (d, 1H); 19F-NMR (376 MHz, acetone-d6, ppm): −138.7 (d, 4F), −140.0 (d, 2F), −156.9 (t, 1F), −157.5 (t, 1F), −158.1 (t, 1F), −164.9 (m, 2F), −165.3 (m, 2F), −167.0 (m, 2F); UV-Vis (toluene:pyridine, 95:5): λmax (ε M⁻¹ cm⁻¹)=436 (4.08×10⁴), 625 (7.66×10³) nm.

1.2. Preparation of 1-Ga.

To a heavy-walled Schlenk flask were added 0.20 g of 1 (0.20 mmol) and 0.57 g GaCl₃ (3.3 mmol) under Ar(g). The flask was chilled in N₂(l) and evacuated. 15 mL Degassed anhydrous pyridine (15 mL) was added to the flask via vacuum transfer. The flask was subsequently sealed and allowed to warm to room temperature. The reaction vessel was heated to 120° C. for 1 h. The pyridine solution was diluted with CH₂Cl₂ and washed with water three times. The solution was then filtered through glass wool and partially concentrated for recrystallization with hexanes overnight. The product was then filtered, dried, and washed with a combination of acetone, CH₂Cl₂, and toluene. This filtrate collected was brought to dryness in vacuo to afford a dark green solid (0.092 g, 38% yield). ESI-MS (CH₂Cl₂:pyridine): m/z: 1056.81 [M-H]⁻ (Calculated for C₃₇H₈N₄F₁₅Cl₂S₂O₄Ga: 1057.82); ¹H-NMR (500 MHz, CD₂Cl₂, ppm): δ=9.99 (s), 8.82 (m), 8.73 (m), 8.57 (m); ¹⁹F-NMR (376 MHz, acetone-d₆, ppm): −138.7 (d), −140.0 (d), −156.9 (t), −157.5 (t), −158.1 (t), −164.9 (m), −165.3 (m), −167.0 (m); UVVis (toluene:pyridine, 95:5): λmax (ε M⁻¹ cm⁻¹)=429 (1.65×10⁴), 611 (5.61×10³) nm.

2. TiO₂ Surface Activation.

To the solid TiO2 nanoparticle (10 g) in a 2.0-L round bottom flask was added 1.2 L 30% H2O2 solution. The milky colloidal suspension was stirred under reflux or 5 h. Upon cooling, the off-white solid was isolated from the H₂O₂ solution by ultracentrifugation at 4° C. and washed with copious amount of water. The activated TiO₂ nanoparticle (TiO₂—OH) collected was dried in vacuo for 12 h and stored dry in a vial prior to use.

3. Surface Conjugation.

The following general procedure was employed for the conjugation of the corroles 1, 1-Al, and 1-Ga to the activated TiO₂ nanoparticle surface: To the mixed solids containing the activated TiO₂ and corrole in a 25-mL round bottom flask was charged with anhydrous pyridine. The suspension turned green immediately and was stirred under reflux before the reaction was stopped. The resulting green solid was isolated from the green solution by centrifugation and washed multiple times with dichloromethane, acetone, and deionized water until the centrifuge supernatant became colorless. The solid remained green, was dried in vacuo, and was stored until further use. The detailed preparation procedure for each corrole nanoconjugate is given as follows:

3.1. Preparation of 1-TiO₂.

To a 25 mL round bottom flask were added 0.32 g TiO₂—OH and 0.028 g of 1 (28.1 μmol), which was subsequently cycled with argon and vacuum. After establishment of the inert atmosphere, 8 mL anhydrous pyridine was added to the flask and the reaction was set to reflux for 2 h. The resulting green solid was collected in a manner following the general centrifugation and washing procedures outlined above.

3.2. Preparation of 1-Al—TiO₂.

To a 40 mL vial was added 1.18 g TiO₂—OH, which was subsequently cycled with argon and vacuum. To this flask, was added 5 mL anhydrous pyridine, followed by sonication to ensure even dispersion. In a second flask, was added 0.03 g of 1-Al (25.5 μmol) and 7 mL anhydrous pyridine under Ar(g). This solution was stirred and then added to the TiO₂—OH precursor via syringe. The reaction was sealed and allowed to reflux for 2 h after which, the resulting green solid was collected in a manner following the general centrifugation and washing procedures outlined above.

3.3. Preparation of 1-Ga—TiO₂.

To a 40 mL vial was added 0.84 g TiO₂—OH and 0.04 g of 1-Ga (32.8 μmol), which was subsequently cycled with argon and vacuum. After establishment of the inert atmosphere, 8 mL anhydrous pyridine was added to the flask and the reaction was set to reflux for 2 h. The resulting green solid was collected in a manner following the general centrifugation and washing procedures outlined above.

Spectroscopies.

UV-Vis spectra were either recorded on a Carey 50 spectrophotometer or a Hewlett-Packard 8453 diode-array spectrophotometer at room temperature from samples in various solvents. IR spectra were recorded with a SensIR Durascope ATR accessory plate on a Nicolet Magna-IR spectrometer, an uncooled pyroelectric deuterated triglycine sulfate (DTGS) etector, and a KBr beamsplitter. The ¹H and ¹⁹F NMR spectra were recorded on a Varian Mercury 300 (300 MHz for 1H; 288 MHz for ¹⁹F) spectrometer. The NMR spectra were analyzed using MestReNova (v. 6.1.1). ¹H NMR measurements were referenced to internal solvents. Fluorescence spectra were measured with a Jobin-Yvonne/SPEX Fluorolog spectrometer (Model FL3-11) equipped with a Hamamatsu R928 PMT. Samples were excited at λex=405-430 nm (the Soret region), 514 nm, and 600-630 nm (Q-band region) with 2-nm band-passes. The fluorescence was observed from λem=500-800 nm, depending on the excitation wavelength, at 2-nm intervals with 0.5 s integration times at room temperature.

Relative Fluorescence Quantum Yield Measurements.

The Φem measurements were performed using degassed toluene solutions of 1, 1-Al, 1-Ga, and tetraphenylporphyrin (as a standard). Samples were excited at λex=355 nm and the emission was observed from λem=500-800 nm. The standard tetraphenylporphyrin was excited at λex=514 nm and the emission was observed from λem=500-800 nm. Φem for tetraphenylporphyrin is 0.11.3 All relative fluorescence quantum yields were calculated based on the corresponding fluorescence spectra of the samples and the standard according to the equation:

${\phi_{em}(x)} = \frac{{A_{s} \cdot F_{x} \cdot \eta_{x}^{2}}{\phi_{em}(s)}}{A_{x} \cdot F_{s} \cdot \eta_{s}^{2}}$

where Φem(s) and Φem(x) are the relative fluorescence quantum yield of the standard and sample, respectively; As and Ax are the absorbance at the excitation wavelength for the standard and sample, respectively; Fs and Fx are the area under the corrected emission curve for the standard and sample, respectively; and ηs and ηx are the refractive index of the solvent used for the standard and sample, respectively.

Mass Spectrometry.

Samples were analyzed by direct infusion ESI in the negative ion mode using an LCT Premier XE (Waters) ESI-TOF mass spectrometer operated in the W configuration. The samples were prepared in CH2Cl2:isopropanol (9:1 v/v) at 10 μM and infused with an external syringe pump at 25 μL/min. Some samples contained 50 μL pyridine in 1 mL CH₂Cl₂:isopropanol mixture.

Surface Characterization.

X-ray photoelectron spectroscopy was performed on an M-Probe spectrometer that was interfaced to a computer running the ESCA2005 (Service Physics) software. The monochromatic X-ray source was the 1486.6 eV Al Kα line, directed at 35° to the sample surface. Emitted photoelectrons were collected by a hemispherical analyzer that was mounted at an angle of 35° with respect to the sample surface. Low-resolution survey spectra were acquired between binding energies of 1 and 1100 eV. Higher-resolution detailed scans, with a resolution of 0.8 eV, were collected on the F(1s) XPS line. All binding energies are reported in electronvolts.

Attenuated total reflectance (ATR) infrared spectra of powdered corrole-TiO₂ nanoconjugate samples were collected using a SensIR Durascope ATR accessory plate on a Nicolet Magna-IR spectrometer, an uncooled pyroelectric deuterated triglycine sulfate (DTGS) detector with a KBr window (400-4000 cm⁻¹), and a KBr beamsplitter. The spectral resolution was 4 cm⁻¹ and 64 scans were collected per spectrum. A KBr background spectrum was subtracted from the measured spectrum of the nanoconjugates to provide the desired FTIR characterization data. See FIGS. 8 and 9.

Confocal Microscopy.

The phantom imaging experiments were performed using a Zeiss LSM 710 Confocal Microscope (Carl Zeiss, Wake Forest, N.C.). The microscope system consists of a Zeiss 710 confocal scanner, 63×/1.4 Plan-APOCHROMAT oil immersion lens (Zeiss), Axio Observer Z1 microscope and diode-pump solid-state lasers. Two visible excitation lines (405 and 561 nm) were used for the experiments. The microscope is equipped with a QUASAR 32 channel spectral detector (two standard PMTs and a 32 channel PMT array) with spectral resolution of 9.7 nm. The software ZEN 2009 was used for hardware control. The laser power used for the experiments is 10% of the total available power (25 mW). ImageJ software was employed to process the resulting data.

Transmission Electron Microscopy.

The morphologies of the TiO2 nanoparticles before and after surface functionalization were imaged using a FEI Tecnai F30ST transmission electron microscope (TEM) operated at acceleration voltage of 300 kV. Images were recorded using a Gatan CCD camera. For TEM analysis, a small quantity of TiO2 particles was dispersed in IPA by sonication. The dispersions were drop-cast onto C-flat™ holey carbon films on a 200 mesh Cu TEM grid (purchased from Electron Microscopy Sciences).

Approximation of Loading of 1-al on TiO₂ Surface.

Calculation of the corrole 1-Al's loading on the surface of TiO₂ was based on the absorbance values obtained from the integrated sphere electronic absorption measurements described as follows.

Absorption Spectroscopy.

Thin film transflectance measurements were used to calculate the dye loading on the TiO₂ nanoparticles. Both peroxide-etched and dye-functionalized nanoparticles were dispersed in a polydimethylsiloxane (PDMS) polymer matrix. The weights of the TiO₂ nanoparticles, PDMS base (Sylgard® 184 silicone elastomer base from Dow Corning), and curing agent (Sylgard® 184 silicone elastomer curing agent from Dow Corning) are provided in Table 1 below. The nanoparticles were first dispersed in a minimal amount of isopropanol (IPA) by sonication. The dispersion of TiO₂ nanoparticles in IPA was then mixed with the PDMS base and curing agent using a Vortex mixer. The mixtures were cast into films onto quartz substrates and allowed to cure in air for 12 hours followed by curing in a drying oven at 60° for 2 hours. See FIG. 3.

TABLE 1 Weights of TiO₂ nanoparticles, weights of the PDMS base and curing agnet used to case PDMS films, weight % TiO₂ in the films, film weight, and mass of TiO₂ per volume of PDMS. Mass Mass Total Est. dry Film Mass TiO₂/ Mass Mass PDMS PDMS weight film weight Weight weight volume PDMS Sample TiO₂ (mg) IPA (g) base (g) curing agent (g) (g) (g)^(a) % TiO₂ (g) (g/L)^(b) Etched TiO₂ 3.35 3.683 0.9266 0.1220 1.4203 1.0593 0.32 0.2901 3.3 1-Al—TiO₂ 3.25 3.234 0.9425 0.1154 1.3846 1.0676 0.30 0.3384 3.2 ^(a)Separate measurements showed that 98% of the IPA evaporated during curing of the PDMS film. ^(b)A value of 0.965 g/cm³ was used for the density of PDMS.

Transflectance spectra of the etched and dye-functionalized TiO₂ nanoparticle films were measured using a Cary 5000 UV-Vis-NIR spectrometer from Agilent Technologies equipped with an integrating sphere (External DRA 1800), a PMT detector, a quartz-iodine lamp for the visible region (350-800 nm), and a deuterium lamp for the ultraviolet region (300-350 nm). Because the TiO₂ nanoparticles cause diffuse scattering of the incident illumination, the PDMS films were placed in the center of the integrating sphere such that both the transmitted, T, and the reflected, R, (including the spectrally reflected and diffusely scattered light) light were collected by the PMT detector. The transflectance measurements allow for the absorbance, A, of the films to be determined by A=−log(T+R). The concentration, C, of the dye within the PDMS films was then calculated using the Beer-Lambert law, A=εCl, where ε is the extinction coefficient of the dye and 1 is the film thickness (determined by profilometry, see below). The absorbance values at 426 and 595 nm (corresponding to the Soret and Q bands of the dye, respectively) for the PDMS film containing the dye-functionalized TiO₂ nanoparticles, the estimated extinction coefficients of the dye at these wavelengths, and the film thicknesses are provided in Table 2 below. The absorbance values for the PDMS film containing the unfunctionalized, peroxide-etched TiO₂ nanoparticles at these wavelengths are also provided, which were subtracted from the absorbance values of the dye-functionalized TiO₂ nanoparticles. The dyeloading was determined to be between 2.3 and 3.5 μmole of dye per grams of TiO₂ (based on whether the Soret or Q band was used to determine the dye concentration).

TABLE 2 Absorption values at 426 and 595 nm and thicknesses for PDMS films containing dyefunctionalized and peroxide- etched TiO₂ nanoparticles, and estimated dye loading of the TiO₂ particles based on absorption measurements. Film Est. dye extinction Film Dye Dye loading Wavelength Dye-functionalized thickness coefficient Etched TiO₂ thickness concentration (μmoles of dye/g (nm) TiO₂ absorbance (cm) (M⁻¹cm⁻¹)^(a) absorbance (cm) (M) of TiO₂) 426 0.170 0.054 4.08 × 10⁴ 0.005 0.054 7.5 × 10⁻⁵ 2.3 595 0.048 0.054 7.66 × 10³ 0.002 0.054 1.1 × 10⁻⁴ 3.5 ^(a)Extinction coefficients measured in toluene:pyridine (95:5) mixture.

Profilometry.

Thickness profiles of the PDMS films were measured using a Bruker DektakXT stylus surface profilometer. The diameter of the diamond-tipped stylus was 2 μm and a weight of 1 mg was applied to the film, respectively. The stylus was scanned at a rate of 250 μm/s. The thickness profiles were used measure the average path length through the PDMS films during the transflectance measurements.

Cell Culture and Cell Viability Assay.

Pathogen-free U87-LUC cell line (TSRI Small Animal Imaging and Research Laboratory) was grown in 75 mL flask in Dulbecco's Minumal Essential Medium (DMEM) in 5% CO₂ at 37° C. The cell culture medium was supplemented with 10% fetal bovine serum (FBS) and 1% the antibiotic primocin. The cell culture medium was replenished every two days and the cells were passaged once they reached 80% confluence. Primary mouse hepatocytes (PMH) were isolated and cultured as previously described.

For U87-Luc cell culture experiments. The cells were plated in an 8-chamber slide (Cultureslide, BD) were treated with 1-Al-TiO2 suspended in PBS over a range of 2 ng/mL to 2 mg/mL. A primary stock solution (6.3 mg 1-Al—TiO₂ in 1 mL PBS) was prepared. The primary stock solution was further diluted to prepare secondary and tertiary stock solutions. The various amount of stock solutions were added to the eight-well glass slide plated with cells to give the aforementioned range of concentrations. The final volume for each well is 300 μL. After treatment, the treated cells and controls were incubated in the dark in 5% CO₂ at 37° C. for a period of 24, 48, and 72 h. The cells were imaged using the cooled IVIS® animal imaging system (Xenogen, Alameda, Calif. USA) linked to a PC running with Living Image™ software (Xenogen) along with IGOR (Wavemetrics, Seattle, Wash., USA) under Microsoft® Windows® 2000. This system yields high signal-to-noise images of luciferase signals emerging from the cells. Before imaging, 0.5 mL of 150 mg/mL luciferin in normal saline was added to each well. An integration time of 1 min with binning of 5 min was used for luminescent image acquisition. The signal intensity was quantified as the flux of all detected photon counts within each well using the LivingImage software package. All experiments were performed in triplicate.

For PMH cell culture experiments, the cells were plated in a 6-chamber slide (Cultureslide, BD). After three hours, media was exchanged (DMEM-F12) and the cells were treated with 1-Al—TiO₂ suspended in PBS over a range of 0.3 ng/mL to 0.3 mg/mL. A primary stock solution (6.3 mg 1-Al—TiO₂ in 1 mL PBS) was prepared. The primary stock solution was further diluted to prepare secondary and tertiary stock solutions. The various amount of stock solutions were added to the eight-well glass slide plated with cells to give the aforementioned range of concentrations. The final volume for each well is 2000 μL. After 24 or 48 h of treatment, cells were double stained with Hoechst 33258 (8 mg/mL) and Sytox Green (1 mmol/L). Quantitation of total and necrotic cells (Sytox Green positive) was performed by counting cells in at least 5 different fields using ImageJ, as previously described. All experiments were done in triplicate.

In Vitro Confocal Fluorescence Microscopy.

The U87-Luc cells were seeded at 20,000 cells per well on an 8-chamber slide (Cultureslide, BD) and allowed to grow overnight. Cells were washed with PBS and were incubated in serum free media mixed 1:1 with 1-Al—TiO₂ for 24, 48, and 72 h at 37° C. over the concentration range similar to the U87-Luc cell viability assay (2 ng/mL to 2 mg/mL). Cells were then washed 3× with PBS and stained with Hoechst 33258 and FM® 1-43FX stains. The cells were chilled on iced and then imaged without being fixed using a Zeiss LSM 710 inverted confocal microscope.

Electronic absorption spectra for 1, 1-Al, and 1-Ga was obtained in degassed toluene. Solutions reveal the signature Soret and Q-bands for these tetrapyrrolic macrocycles (FIG. 1). The electronic absorption data for the chlorosulfonated corroles are also given in Table 3.

TABLE 3 Electronic spectroscopic data for chlorosulfonated corroles 1, 1-A1, and 1-Ga in toluene solution Electronic Absorption^(a) Fluorescence^(a) Corrole λ_(max) ^(b) (nm) λ_(ex) (nm) λ_(ex) (nm) φ_(em) ^(c) 1 430 (S) 426 670 0.094 580 (Q) 1-Al 424 (S) 420 611 0.127 592 (Q) 1-Ga 426 (S) 427 609 0.099 588 (Q) ^(a)The measurements were performed in degassed toluene. ^(b)The maximum absorption wavelengths are reported for both Soret (S) and Q-bands (Q). ^(c)The relative emission quantum yields were determined using tetraphenylporphyrin as a standard.

The electronic absorption spectra of the colloidal suspensions of 1-TiO₂, 1-Al—TiO₂, and 1-Ga—TiO₂ nanoconjugates in PBS pH 7.4 reveal maximum absorptions centered around 425 and 600 nm for the Soret and Q-bands, respectively (Table 4).

TABLE 4 Electronic absorption, vibrational, and X-ray photoelectron spectroscopic data for corrole-TiO₂ nanoconjugates 1-TiO₂, 1-Al—TiO₂ and 1-Ga—TiO₂ Electronic SO₂ Vibrational Absorption Frequency (cm⁻¹) F(1s) Binding Conjugate λ_(max) (nm) Sym Asym Energy (eV) 1-TiO₂ 415, 430 (S) 1153 1410 691 591, 621 (Q) 1-Al—TiO₂ 427 (S) 1244 1431 690 576, 610 (Q) 1-Ga—TiO₂ 423 (S) 1160 1450 688 589, 610 (Q)

These peak maxima are in agreement with the spectroscopic properties of the corresponding molecular corrole (Table 3). The Soret band splitting for 1-TiO₂ is similar to the splitting observed for its amphiphilic molecular counterpart 2,17-bissulfonato-5,10,15-tris(pentafluorophenyl) corrole in an aqueous solution at physiologic pH, supporting the presence of the sulfonate linkage on the corrole anchored to TiO₂ surfaces. The splitting pattern, however, was not observed for the metalloconjugates 1-Al—TiO₂ and 1-Ga—TiO₂, owning to the presence of metal bound to deprotonated nitrogen atoms.

Characterization of the fine green powder of 1-TiO₂, 1-Al—TiO₂, and 1-Ga—TiO₂ with FT-IR spectroscopy reveals vibrational absorption bands around 1180-1250 cm⁻¹ assigned to the symmetric stretching of SO₂ groups as well as those around 1400-1450 cm⁻¹ assigned to asymmetric stretching of SO₂ groups of covalent sulfonates. The presence of these vibrational signatures suggests that the corroles are covalently attached to the surface of TiO₂ through a sulfonate linkage. The vibrational frequencies for these TiO₂-corrole nanoconjugates are listed in Table 2. X-ray photoelectron spectroscopy was performed to study the elemental presence of the surface of the nanoparticle conjugates (Table 4). High-resolution scans for the spectra of the conjugates revealed F(1s) binding energy peaks between 688 and 691 eV, suggesting the presence of corresponding pentafluorophenyl corroles attached to the TiO₂ surface. See FIG. 10.

Confocal fluorescence microscopy images of aggregates of the nanoconjugates 1-TiO₂, 1-Al—TiO₂, and 1-Ga—TiO₂ in the solid state (FIG. 1) were taken with the samples illuminated at λ_(ex)=405 nm and the λ_(em) recorded from 508 to 722 nm. The images for 1-Al—TiO₂ and 1-Ga—TiO₂ (FIGS. 1 e and 1 h) exhibit fluorescence areas on the nanoparticles compared to the relatively darker image for 1-TiO₂. The fluorescence signals observed with various intensities across the TiO₂ samples for 1-Al—TiO₂ and 1-Ga—TiO₂ also suggest that the TiO₂ surfaces are not evenly functionalized because of material aggregation. Selected fluorescence areas (white circles) on all three images, spectral profiles representing the nanoconjugates 1-TiO₂, 1-Al—TiO₂, and 1-Ga—TiO₂ were obtained (FIGS. 1 c, 1 f, and 1 i). These spectral profiles and fluorescence signal intensities are in agreement with the fluorescence spectra (FIGS. 1 a, 1 d, and 1 g) obtained from the molecular corroles 1, 1-Al, and 1-Ga.

The nanoconjugate 1-Al—TiO₂ was chosen as a candidate for cellular uptake and cytotoxic effect studies. The TEM images of TiO₂ (FIG. 2) show the average particle size to be 29 nm, post-corrole functionalization, albeit, they appear to aggregate. Images were taken for both before and after surface functionalization as well as for both before and after H₂O₂-etching. Absorption measurements of the particles embedded in a transparent polymer matrix, facilitated with the use of an integrating sphere, indicate nearly identical absorption features in the molecular and conjugated species. These experiments afforded an approximate loading of 1-Al on the surfaces of ca. 10-40 mg/g TiO₂. (FIG. 2).

Treatment of the luciferase-transfected glioblastoma cell U87-Luc with a wide range of 1-Al—TiO₂ concentrations (2 ng/mL to 2 mg/mL) reveals internalization of these nanocojugates over a period of 24, 48, and 72 h as shown by the confocal fluorescence microscopic (CFM) images (FIG. 4).

The CFM images were taken after the cells were stained with the nuclear and cell membrane dyes, and washed with the media solution several times to remove the excess dyes and 1-Al-TiO2 nanoconjugates. The nucleus labeled with a Hoechst stain is seen in bluish purple (λex=405 nm, λem=460 nm). The membrane seen in green is labeled with the dye FM® 1-43FX (λex=488 nm, λem=580 nm). The nanoconjugate 1-Al—TiO₂ is observed in red (λex=405 nm, λem=634 nm).

The Z-stacked confocal fluorescence microscopic (CFM) images (FIG. 5) of U87-Luc cells treated with similar concentrations (2 ng/mL to 2 mg/mL) of 1-Al—TiO₂ for 48 and 72 h from three different perspectives are also shown (FIG. 5). The Z-stacked CFM images of individual cells were taken at 0.5-μm slice intervals from top to bottom.

The 1-Al—TiO₂ nanoconstruct could also be internalized through endocytosis. Based on the confocal fluorescence images, the nanomaterials 1-Al-modified TiO₂ is suspended in the cytosol as opposed to the modified TiO₂ labeled with alizarin red S, which showed perinuclear localization in HeLa cells. These findings suggest a distribution pattern of the TiO₂ nanoconjugates within the cells similar to another study, in which 1-D TiO₂ nanorods and nanoparticles labeled with fluorescein thiocyanate were internalized into HeLa cells after a given period of time. The internalization of 1-Al—TiO₂ into glioblastoma cells can also be observed even at a very low concentration range (<μg/mL).

TiO₂ nanoparticles exhibit various degrees of cytotoxic activities upon photoactivation by UV-Vis light leading to formation of reactive oxygen species. To best study and understand the cytotoxic effect of the 1-Al—TiO₂ conjugate that is not related to the photocatalytic property of TiO₂ on cell death, the glioblastoma cell U87-Luc was treated in the absence of UV-Vis irradiation with the same range of 1-Al—TiO₂ concentrations (2 ng/mL to 2 mg/mL) as in the cell internalization studies. The cells were incubated over a period of 24, 48, and 72 h prior to bioluminescence cell viability assays. Based on the bioluminescence signal of the firefly luciferin from living U87-Luc cells, which is related to the level of cellular ATP, the cytotoxic assay shows that the nanoconjugate 1-Al—TiO₂ has essentially no cytotoxic effect on the glioblastoma cells after 24 h of treatment (FIG. 6) and, therefore, could be considered biocompatible. On the other hand, the cytotoxic effect becomes more apparent as the cells were exposed to the corrole-TiO₂ nanoparticles for extended periods of time at higher concentrations (>200 μg/mL). For example, only ca. 65% and ca. 30% of the bioluminescence signals from the live cells were observed after the 48-h and 72-h treatments at 2 mg/mL, respectively. This viability study of the U87-Luc cells treated with 1-Al—TiO₂ is also consistent with a study performed on mouse fibroblast cells, using the MTT assay, showing that the cytotoxic effects of TiO₂ at various concentrations (3 to 600 μg/mL) were negligible after 24 h of treatment whereas the 48-h treatment of these cells with the nanoparticle showed decrease in cell viability at higher concentrations. Another study on the cytotoxicity effect of unmodified 1-D and 3-D TiO₂ on HeLa cell also show that these nanoparticles were relatively nontoxic at concentrations up to 125 μg/mL in the absence of light.

Additionally, to compare the cytotoxic effect of the nanoconjugate 1-Al—TiO₂ on cancer and normal cells, mouse primary hepatocytes (MPH) were treated with 1-Al—TiO₂ in various concentrations (0.3 ng/mL to 0.3 mg/mL) for 24 and 48 h (FIG. 7). It was observed that 1-Al—TiO₂ was also essentially nontoxic up to 3 mg/mL after both 24 and 48 h of treatment. Only at higher concentrations were the ratios of the live cells dropped below 80%. The MPH behave similarly after 24-h and 48-h treatments with various doses of 1-Al—TiO₂, suggesting that low 1-Al—TiO₂ concentrations have minimal cytotoxic effects on the viability of these normal cells. While the trend at high concentrations were not observed for the glioblastoma U870-Luc cells treated with 1-Al—TiO₂, it is expected that normal cells, especially primary cells, are less tolerant towards exogenous non-native agents. Nonetheless, the intense fluorescence exhibited by 1-Al would allow for the use of the nanoconjugate 1-Al—TiO₂ as an optical imaging agent observable by confocal fluorescence microscopy even at low concentrations (20-200 ng/mL) below the cytotoxic thresholds for both the cancer and normal cells observed in the studies.

4-(chlorosulfonyl)Benzoic Acid+TiO₂ (Anatase)

Added TiO₂ (0.1099 g) and 4-(chlorosulfonyl)Benzoic Acid (0.0171 g) to scintillation vial. Pumped into dry box. Added anhydrous Pyridine (3 mL) and heated to 120° C. for 1 hr, under an inert atmosphere. Allowed to cool to room temperature, then added 2 mL H₂O, which then centrifuged down. Washed and centrifuged with acetone, acetone, water, and acetone. Pumped down on high vacuum line to afford product for Infrared Spectroscopy.

Biphenyl-4-sulfonyl Chloride+TiO₂ (Anatase)

Added TiO₂ (0.1253 g) and Biphenyl-4-sulfonyl Chloride (0.0208 g) to scintillation vial. Pumped into dry box. Added anhydrous Pyridine (3 mL) and heated to 120° C. for 1 hr, under an inert atmosphere. Allowed to cool to room temperature, then added 2 mL H₂O, which then centrifuged down. Washed and centrifuged with acetone, acetone, water, and acetone. Pumped down on high vacuum line to afford product for Infrared Spectroscopy.

4′-chlorobiphenyl-4-sulfonyl Chloride+TiO₂ (Anatase)

Added TiO₂ (0.1205 g) and 4′-chlorobiphenyl-4-sulfonyl Chloride (0.0210 g) to scintillation vial. Pumped into dry box. Added anhydrous Pyridine (3 mL) and heated to 120° C. for 1 hr, under an inert atmosphere. Allowed to cool to room temperature, then added 2 mL H₂O, which then centrifuged down. Washed and centrifuged with acetone, acetone, water, and acetone. Pumped down on high vacuum line to afford product for Infrared Spectroscopy.

Chlorsulfonyl Isocyante+TiO₂ (Anatase)

Added TiO₂ (0.1205 g) to scintillation vial. Pumped into dry box. Added 100 μL Chlorsulfonyl Isocyante. Added anhydrous Pyridine (3 mL) and heated to 120° C. for 1 hr, under an inert atmosphere. Allowed to cool to room temperature, then added 2 mL H₂O, which then centrifuged down. Washed and centrifuged with acetone, acetone, water, and acetone. Pumped down on high vacuum line to afford product for Infrared Spectroscopy.

Chlorsulfonyl Isocyante+TiO₂ (Anatase)

Added TiO₂ (0.1269 g) to scintillation vial. Pumped into dry box. Added 400 μL Chlorsulfonyl Isocyante. Heated to 120° C. for 1 hr, under an inert atmosphere. Allowed to cool to room temperature, then added 4 mL H₂O, which was then centrifuged down. Washed and centrifuged with acetone, acetone, water, and acetone. Pumped down on high vacuum line to afford product for Infrared Spectroscopy.

According to the methods described herein, other Cl—SO₂-containing substrates can also be employed, such as, for example, 2-pentyl sulfonyl chloride, 3,3,3-trifluoropropane-1-sulfonyl chloride, methyl(chlorosulfonyl)acetate, and the like. 

What is claimed:
 1. A method of making a material of formula I

wherein A is corrolyl or metallated corrolyl group and n is 0 or 1; and M is a surface comprising TiO₂, BaTiO₃, Al₂O₃, Fe₂O₃, Fe₃O₄, ZrO₂, CeO₂, CdO, Cr₂O₃, CuO, MnO, Mn₂O₃, MnO₂, NiO, SnO, SnO₂, SiO₂, or ZnO; comprising contacting a surface comprising TiO₂, BaTiO₃, Al₂O₃, Fe₂O₃, Fe₃O₄, ZrO₂, CeO₂, CdO, Cr₂O₃, CuO, MnO, Mn₂O₃, MnO₂, NiO, SnO, SnO₂, SiO₂, or ZnO, the surface having at least one —OH group with a compound of formula III: (Cl—SO₂)_(m)-A  (III) wherein m is 1 or
 2. 2. The method of claim 1, wherein the surface is a nanoparticle surface.
 3. The method of claim 1, wherein the material is

wherein Ar is phenyl or naphthyl, wherein the phenyl or naphthyl is optionally substituted with one or more substituents independently selected from the group consisting of halogen and —NR³R⁴, wherein R³ and R⁴ are each independently H, C₁₋₁₀alkyl, C₁₋₁₀alkenyl, or -alkaryl; or R³ and R⁴, together with the nitrogen atom to which they are attached, form a heterocycloalkyl ring that is optionally substituted with C₁₋₆ alkyl; and wherein one or two of R² is M-O—SO₂— and the remaining R² groups are independently H, C₁₋₆alkyl, or halogen.
 4. The method of claim 1, wherein the material is

wherein D is Al, Ga, Fe, Mn, Sb, Co, Cr, Rh, Ru, Ro, Ir, V, Re, Cu, Sn, Ge, Ti, or Mo, each of which is optionally coordinated to one or more ligands; Ar is phenyl or naphthyl, wherein the phenyl or naphthyl is optionally substituted with one or more substituents independently selected from the group consisting of halogen and —NR³R⁴, wherein R³ and R⁴ are each independently H, C₁₋₁₀alkyl, C₁₋₁₀alkenyl, or -alkaryl; or R³ and R⁴, together with the nitrogen atom to which they are attached, form a heterocycloalkyl ring that is optionally substituted with C₁₋₆ alkyl; and wherein one or two of R² is M-O—SO₇— and the remaining R² groups are independently H, C₁₋₆alkyl, or halogen.
 5. A material of formula I:

wherein A is a corrolyl or metallated corrolyl group; M is a surface comprising TiO₂, BaTiO₃, Al₂O₃, Fe₂O₃, Fe₃O₄, ZrO₂, CeO₂, CdO, Cr₂O₃, CuO, MnO, Mn₂O₃, MnO₂, NiO, SnO, SnO₂, SiO₂, or ZnO; and n is 0 or 1, wherein the material is made by the method of claim
 1. 6. The material according to claim 5, wherein the surface is a nanoparticle surface.
 7. The material according to claim 5, wherein the materials is:

wherein Ar is phenyl or naphthyl, wherein the phenyl or naphthyl is optionally substituted with one or more substituents independently selected from the group consisting of halogen and —NR³R⁴, wherein R³ and R⁴ are each independently H, C₁₋₁₀alkyl, C₁₋₁₀alkenyl, or -alkaryl; or R³ and R⁴, together with the nitrogen atom to which they are attached, form a heterocycloalkyl ring that is optionally substituted with C₁₋₆alkyl; and one or two of R² is M-O—SO₂— and the remaining R² groups are independently H, C₁₋₆alkyl, or halogen.
 8. The material according to claim 7, wherein the materials is:


9. The material according to claim 8, wherein each Ar is pentafluorophenyl.
 10. The material according to claim 5, wherein the material is:

wherein D is Al, Ga, Fe, Mn, Sb, Co, Cr, Rh, Ru, Ro, Ir, V, Re, Cu, Sn, Ge, Ti, or Mo, each of which is optionally coordinated to one or more ligands; Ar is phenyl or naphthyl, wherein the phenyl or naphthyl is optionally substituted with one or more substituents independently selected from the group consisting of halogen and —NR³R⁴, wherein R³ and R⁴ are each independently H, C₁₋₁₀alkyl, C₁₋₁₀alkenyl, or -alkaryl; or R³ and R⁴, together with the nitrogen atom to which they are attached, form a heterocycloalkyl ring that is optionally substituted with C₁₋₆ alkyl; and one or two of R² is M-O—SO₇— and the remaining R² groups are independently H, C₁₋₆alkyl, or halogen.
 11. The material according to claim 10, wherein D is Al or Ga.
 12. The material according to claim 10, wherein the material is


13. The material according to claim 12, wherein each Ar is pentafluorophenyl.
 14. The material according to claim 10 wherein D is Al(ligand)₂ or Ga(ligand).
 15. The material according to claim 14, wherein the ligand is pyridine.
 16. The material according to claim 5, wherein n is
 0. 17. The material according to claim 5, wherein n is
 1. 18. The material according to claim 5 that is:

wherein Ar is phenyl or naphthyl, wherein the phenyl or naphthyl is optionally substituted with one or more substituents independently selected from the group consisting of halogen and —NR³R⁴, wherein R³ and R⁴ are each independently H, C₁₋₁₀ alkyl, C₁₋₁₀ alkenyl, or -alkaryl; or R³ and R⁴, together with the nitrogen atom to which they are attached, form a heterocycloalkyl ring that is optionally substituted with C₁₋₆ alkyl, and py is pyridine.
 19. The material according to claim 18, wherein each Ar is pentafluorophenyl.
 20. The material according to claim 18, wherein M is TiO₂.
 21. A method of imaging cancer in a patient comprising; administering to the patient a material according to claim 5, wherein A is a metallated corrolyl group; and imaging cancer cells using optical imaging.
 22. The method of claim 21, wherein the optical imaging is fluorescence imaging.
 23. The method of claim 21, wherein the cancer is glioblastoma, melanoma, breast cancer, liver cancer, or colon cancer.
 24. The method of claim 21, wherein the material is

wherein Ar is phenyl or naphthyl, wherein the phenyl or naphthyl is optionally substituted with one or more substituents independently selected from the group consisting of halogen and —NR³R⁴, wherein R³ and R⁴ are each independently H, C₁₋₁₀ alkyl, C₁₋₁₀ alkenyl, or -alkaryl; or R³ and R⁴, together with the nitrogen atom to which they are attached, form a heterocycloalkyl ring that is optionally substituted with C₁₋₆ alkyl, and wherein py is pyridine.
 25. The method of claim 24, wherein Ar is pentafluorophenyl.
 26. The method of claim 23, wherein M is TiO₂. 